SHERIDAN, Wyo. — Organic artifacts preserved by ice patches in Yellowstone National Park are being lost to research because warmer temperatures are melting the ice, an archaeologist said.

Before his current position leading the cultural and natural resources program at Little Bighorn Battlefield National Monument in Montana, Staffan Peterson was park archaeologist at Yellowstone for four years.

Peterson told members of the Sheridan-Johnson County Chapter of the Wyoming Archaeological Society this past week that archaeologists can't collect the organic pollen, pine needles, sticks, dung, bones and other artifacts preserved in the ice patches.

"They're cryogenically preserved, and so once that stuff melts, that protection's gone, and these things will decay very quickly," he said. "I mean they're ancient and they've been in the ice — entombed in this ice for millennia — and they don't stand a chance out in the open air."

Archaeologist Sarah Mostek of Hope Archaeology in Bozeman, Montana, told the Sheridan Press that this was the first time that she's heard of ice patch archaeology.

Peterson said he and other scientists and park officials initially got the sense that something was changing in the higher Yellowstone elevations about 10 years ago and have since done reconnaissance to determine where the ice patches are and to track their size. He said in the four times they've revisited the ice patches, the changes have been drastic.

"We've seen a marked decrease," Peterson said.

Peterson said artifacts preserved in ice patches in Yellowstone are critical in understanding the bigger picture of the human past.

"It's really an unparalleled storehouse of information that is vanishing," Peterson said.

He said that while this isn't just a problem in the world's first national park, there's only about a dozen ice patches left in Yellowstone. While some are very large, he said the smaller areas won't last much longer.

Peterson said the next time they'll get to return to these areas in Yellowstone is 2019 with funding from the National Park Service.

He said Grand Teton National Park also puts a lot of effort into recovering artifacts from ice patches and researchers will head to those areas sooner than they will in Yellowstone.